run --command parsing not working

Description

When I try to use opencode run --continue --command undo (or /undo or any variant thereof) I get an "unknown error" and the session is not updated in any way.

I know the session is good because I can open it in the TUI and manually run /undo and it works fine.

redo is broken in the same way.

Logs look like this (truncated for privacy)

timestamp=2026-09-10T02:05:43.597Z level=INFO run=6481ecc4 message="all LSPs are disabled"
timestamp=2026-09-10T02:05:43.598Z level=INFO run=6481ecc4 message=init
timestamp=2026-09-10T02:05:43.724Z level=INFO run=6481ecc4 message="event connected"
timestamp=2026-09-10T02:05:43.728Z level=INFO run=6481ecc4 message=command session.id=ses_f76f9c50affeLlpZlbLKZ47KiM command=redo agent=undefined
timestamp=2026-09-10T02:05:43.756Z level=INFO run=6481ecc4 message=init count=3
timestamp=2026-09-10T02:05:43.758Z level=ERROR run=6481ecc4 message=failed ref=err_bcf8cb0b error="UnknownError: UnknownError" cause="UnknownError: UnknownError\n    at <anonymous> (/$bunfs/root/chunk-9ka1yn5k.js:1142:15768)\n    at SessionPrompt.command (/$bunfs/root/chunk-6kdffn5w.js:4:14009)\n    at SessionPrompt.command (definition) (/$bunfs/root/chunk-9ka1yn5k.js:1142:15495)\n    at SessionHttpApi.command (/$bunfs/root/chunk-6kdffn5w.js:2:84434)\n    at SessionHttpApi.command (definition) (/$bunfs/root/chunk-6kdffn5w.js:4:13919)"
Error: {
  "name": "UnknownError",
  "data": {
    "message": "Unexpected server error. Check server logs for details.",
    "ref": "err_bcf8cb0b"
  }
}
timestamp=2026-09-10T02:05:43.759Z level=INFO run=6481ecc4 message="disposing instance"

Plugins

No response

OpenCode version

1.18.30

Steps to reproduce

1. opencode run create an empty file called test.txt in this directory
2. opencode run --continue --command undo

Expected: snapshot is rolled back
Actual: "Unexpected server error"

Note that if I just do opencode run --continue /undo the changes usually get undone but its the LLM manually reversing its work, not the actual opencode undo functionality which is extremely valuable and a shame to lose when running headless.

Screenshot and/or share link

No response

Operating System

Ubuntu

Terminal

ghostty